STRC according to Saylor: "It’s meant to be like a money market". The "money market" alternative:

Saylor has repeatedly compared STRC to a high-yield money market. STRC is currently under $92. I can't remember the last time I've seen a High Yield Savings Account return negative 8% in a single month.

This is chart from the weekend is already outdated since STRC dropped another 3.5% today even though BTC only dropped 1%. Somehow this supposedly-stable, bank-like STRC has been behaving more volatile than BTC lately. Cracks are showing.